Correction to: Nature Chemistry https://doi.org/10.1038/s41557-018-0172-y, published online 03 December 2018.

In the version of this Article originally published, in the graphical abstract the y-axis units of the plot read ‘mA cm–2’, but should have read ‘μA cm–2’. Additionally, an erroneous gap appeared in the red trace. These errors have now been corrected.